• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Pre-amp not balance when measures with a DMM

I use a volume control on my mono-block amps.

When I set up a stereo system, I turn the volume controls full on the pair of mono-blocks,
and have a 20 step volume control with precision matched resistors.
Any serious lack of balance is due to the room, speakers, and recording.